Optical Filter-Based FBG Sensor Interrogator Unit for Low-Cost Sensing

Fiber Bragg grating (FBG) optical sensors have excellent sensitivity, small size, and immunity to electromagnetic interference. These characteristics make them appealing for a wide range of applications. However, a rather expensive data processing equipment limits practical applicability especially in cases of a single or couple of sensors in remote nodes. The authors propose a simple and compact FBG sensor interrogator device containing broadband light source, optical filter, small form-factor pluggable (SFP) optical transceiver-based photodetector, and microcontroller. This article describes the developed interrogator unit’s prototype and its principle of operation. It is tested using a mechanical strain FBG sensor. The estimated range of strain measurement is up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$420~\mu $ </tex-math></inline-formula> m/m and the minimum sensitivity around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~\mu $ </tex-math></inline-formula> m/m with measurement update rate every 40 ms.